The short story is a series of vignettes following a man that the reader would normally despise. In each vignette the man commits a deplorable act which eventually is seen to make sense. In the first vignette he is on a space ship traveling from Mars (I think) which has an environmental problem necessitating that one of the crew either be killed or be willing to sacrifice himself. The man is the least popular member but is able to convince the crew through logic that another person should be killed instead. The story follows him until at the end after many years, he is the president of the Earth Alliance, or something like that, and the Earth discoveries that an extra-solar species has launched an attack on the solar system which will result in the destruction of most of humanity and its colonies. (One of those is a hollowed out asteroid filled with genetically altered humans with multiple arms. I think they are referred to as ant-people.) The man as president gets on television and tells everyone listening to get a weapon, go through their neighborhood, and kill as many people as possible in order to survive the coming catastrophe.